The present invention relates to a cluch damper for absorbing vibrations occurring during transmission of torque in a clutch mechanism.
The clutch mechanism, which intermittently transmits torque transmitted from a driving portion, normally has a natural frequency caused by resiliency possessed by a driving system forming member and has disadvantages in that not only a resonance phenomenon is generated due to specific torque variation to produce noises but inferior torque transmission occurs. In the past, the clutch mechanism is provided with vibration absorbing means such as a spring, a resilent rubber member or the like.
FIG. 16 shows a conventional clutch damper of a single shearing type which uses a resilient rubber member as the vibration absorbing means. This means has an approximately cylindrical shape comprising a hub a having a flange b integrally formed at one end thereof and having a spline formed in the inner periphery thereof, a clutch plate c approximately in the form of a double ring and arranged opposite to a flange b of the hub a, and a buffer rubber d formed into an annular body made of a rubber-like resilient material, the buffer rubber d being baked between said both members b and c, whereby the vibration is absorbed by the resiliency of the buffer rubber d.
However, since the torsional resiliency of the aforementioned single shearing type clutch damper is constant, the vibration cannot be absorbed effectively irrespective of the magnitude of transmission torque. More specifically, in the case where for example, in the clutch of an automobile, the buffer rubber is set so as to have a rigidity which withstands a great torque, there arises a problem in that a sufficient vibration absorbing power cannot be obtained in a low torque state during idling or the like.
In addition, in a clutch damper which makes use of a compression resiliency of a coil spring as the buffer means, a torsional angle for the buffer is restricted by a compressible amount of the coil spring, and therefore a large torsional angle cannot be empolyed; which is disadvantageous in terms of absorption of vibration.